Friction-spring.



R. D. GALLAGHER, JR.

FRICTION SPRING.

APPLICATION FILED IuNE I9. 1915.

Patented Feb. 1, 1916.

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5M m y R. n. GALLAGH'ER, JR. FIIIC'I'ION` SPRING.

APPLICATION FILED JUNE I9, 1915.

Patentedl Feb. 1, 1916.

LM' 2 SHEETS-SHEET?. 9. 7a v@5675 85a 7, A 7 cI9 I I E RICHARD D. GALLAGHER, Jn., or Niiw YORK, ii. Y.

FRICTION-SPRING.

Application filed J une 19, 1915.

To all whom 'it may concern.'

Be it known that I, RICHARD D. GALLA- eiinii, Jr., a citizen of the United States, residing at New York, in the county and State of New Ycrk. have invented certain springs, and more particularly to frictionl springs of the general type disclosed in my Patent No. 1,146,933 granted to me July 20, 1914, the features of the invention, however, being applicable to any structure designed for the purposeof yieldingly resisting the relative movement of parts.

1n springs of the type referred to, the main resilient elements, and between which the major portion of the friction is created, are resilient helices, preferably an inner and an outer helix. One lhelix is nested within the other helix, with the convolutions alternatedl and lying partially between each other, so as to engage, create friction, and be put under radial stress, by pressure axially of the helices.'

The primary object of the present inven' tion is the provision of an improvedr casing for the mai-n resilient elements of the spring, which, in addition to affording a proper protective covering for the resilient elements, supplements and increasesthe'resistance of the helices to radial expansion under compression and also expands and contracts axially Cr longitudinally with the helices. -Hence, while the helices are maintained in heir proper relative positions and their resistance to axial pressure is augmented by the improved casing, with a corresponding increased efficiency of the spring, the possibility of jamming 'when under stress is avoided by the inherent resiliency` of the casing, both radially and axially.

ln addition to generally improving the construction of a friction spring, lanother object of the invention is the provision of a novel arrangement for assemblinothe-Cps L D j v at each end of the spring, whereby the caps are securely locked against radial, and axial or longitudinal displacement and at the same time are capable of easy detachment, when it is desired to disinounttlie spring,

Speccation of Letters Patent.

`Patented Feb. 1, 1916.

semi No. 35,149.

A full understanding of the invention will l be attained from the ensuing detailed description of a construction embodying the same, in a preferred form when taken in connection with the accompanying drawings, and the novel features of the invention will be particularly pointed out and specified in the appended` claims.

In the drawings: Figure'l is a side elevation of a 'friction spring embodying the present improvements. Fig. 2 is anaxial or lon itudinal section taken on planes indicated y the line 2 2 of Fig. 1. Fig. 3 is a side elevation of the spring with the casing in section and showing a preferred arrangement of the outer friction coil. Fig 4e .is an end elevation of the several coils of the spring with the casingremoved. Fig. 5 is a fragmentary end elevation looking in the direction of the arrow 5 of Fig. 1. Fig. 6 is a fragmentary end elevation looking in the direction of the arrow 6 of Fig. 1. Fig. 7 is a plan View of the inner face of one of the caps. y

Liker characters of'reference inthe several figures indicate the same parts.`

The spring illustrated in the accompanyi ing drawings includes the main resilient elements, these consisting of an inner helix 2 and an outer helix 3. l/Vithin the main resilient elements is, preferably, helical spring l. inner helix 2 is nested within outer helix 3, withthe convolutions of outer helix 3 lying partially between. the convolutions -of inner helix 2. Consequently, when axial pressure is applied to the nested helices, they are put under radial stress, and the convolutions of the helices vtend topress toward each other. In thev preferred construction the inner helix 2 is provided with oppositely inclined outer friction facesV 4 and o'uter helix 3 is provided with oppositely inclined inner friction faces 5. The inclined friction faces 4 and 5 of the respectivehelices 2 and 3 are normally in engagement, e., when the nested helices are expanded and free from axial stress. Accordingly, when axial pressure isbrought to Abear von the nested helices, the friction between engaged faces 4 and 5 is greatly increased, resulting in radial expansion of the nested helices. In practice it has been found ,necessary to construct the outer helix, atleast, in sections lin order to prevent jamming of the nested friction elements, when under axial stress, and when Vthey `are expanding radially. As

sho-wn, in the drawings, the outer helix 3 is made up of a plurality of sections 3, 3b, 3. Each section expands radially independently of the other when under stress, and the proximate ends of sections 3, 3b, for instance, separate when radially expanded,

and approach each other, when radially contracted, A friction springconstructed of inner and outer nested helices alone, however, dees not offer the proper resistance to axial pressure, and, the normal resistance of the nested friction elements, in fact, isl materially diminished by constructingv the outer helix 3 in sections, since it thereby expands much more freely under stress. rlhe present invention provides a novel casing, surrounding the friction elements, which sup* pleinents and increases their resistance to axial pressure'and consequent radial expansion, and, at the same time, the casing is inherently resilient both axially and radially so that jamming of the nested elements is avoided. ln addition, the casing affords an eflicient protective cover for the inner main resilient elements of the spring.

A preferred form of casing is .illustrated in the accompanying drawings, reference being made particularly to Figs. 1, 2 and 3. As shown therein, the casing is in the form of a flat helical spring element 6 which almost completely surrounds the inner elements of the spring. lt is preferable to construct the casing of a plurality of intercalated fiat springs, such as the two intercalated springsk T and 8 shown. This mode of constructicn permits each spring to be made of considerably steeperpitch than the inner spring elements, and while affording proper resiliency of the casing, bcth radially and axially, provides at the same time a substantially continuous casing which pro-A vides an adequate protectirn for the inclosed elements of the spring. The outer faces of the Ahelix 3 are flattened as shown at 3c to frictionally engage the inner-flat faces 7a, 8il of the respective casing coils.

The improved casing surrounds and engagesA the main resilient elements of the spring. While the casing supplements and increases the resistance of the resilient elements to axial stress, its inherent resiliency permits them to expand radially, and prevents jairming under severe strains. In addition, the casing is expansible and contractible axially with the main resilient elements, thereby permitting it to surround themy for practically their entire extent, and

also greatly naci-easing` the resistance and at the same time, the efficiency of the spring.

A further improvement made by the invention is the provision of a novel arrangement for assembling and securely fastening the caps at the respective ends of the spring. When assembled, the caps arev not only se'- curely locked against: longitudinal displacement when the spring expands and the strain of the expanding coils is brought to bear on the caps, but are also prevented from becoming displaced radially with respect to each other. This permits the caps to be utilized to. prevent creepingv of the main resilient elements and also of the intercalated flat coils which form the protective casing for the inner elements of the spring. The construction of the caps is best illustrated in Figs. 2, 5, 6 and 7. As shown, the cap 9, at one end of the spring, z'. e., to the right of Fig. 2, is provided with a central in-turned sleeve 10, having a longitudinal opening 1l. Said longitudinal opening 11 is elongated transversely as shown in Fig. 5, and extends fromv the outer face of the cap 9 to an inner pin or bar vreceiving opening 12, substantially circular in cross section and the diameter of which is approximately equal to the smaller transverse dimension of longitudinal opening 11. This construction proides opposed upper and lower flanges and 1i-l at the inner end of bar re .fing openii 5 12. Extending through openingr 12 is the hollow shank 15 of a cap-connecting bar, which bar is passed through the coils of the inner helical spring 1'. The end of the shank 15 adjacent cap 9 is provided with a head 16, substantially similar in cross section to the longitudinal opening 1l. Said head 16 is received within opening 11 and the inner end of the head1 adjacent to shank 15 extends oppositely from the shank, as shown in Fig. 2, to provide upper and lower shoulders 17 and 18 which abut against upper and lower flanges 13 and 14, respectively, and limit the inward movement of the bar. As shown in Fig. 2, head 15 is tapered from its inner to its outer end to permit `easy insertion and removalr of the head in longitudinal opening 1l'. To facilitate milling of the shank 15 heady 16 is also made hollow.

Ait the opposite end of the spring is a cap 19 having a central in-turned sleeve 20, with a. central opening 21 extending from the outer face of the cap to the inner end of sleeve 20. Opening 21 is substantially circular in cross section and its diameter is approximately equal to the diameter of barreceiving opening 12 of cap 9. Sleeve 20, however, is of the same diameter as sleeve 10 of cap Arranged radially around the circular bore of opening 21 is a series of longitudinal slotsl 22. Each slot 22 extends from the outer face of cap 19 inwardly part way along opening 21, thus providing a shoulder 23 at the inner end of each slot. The several slots 22 are so spaced'about the bore of the opening 21 that oneslot is diametrically opposite another slot and accordingly the cor responding shoulders 23 are diametrically opposite each other. The end 2li of shank 15, adjacent' to cap 19, is taperedl slightly, as shown-in Fig. 2, and is providedvvith a transverse or axially extending squared slot 25 in which is received a key 26. For convenience in milling the tapered end 24 may be bored longitudinally, as shown.

ln assembling the caps at the opposite ends of the spring, the cap-connecting bar is inserted through cap 9, shank. 15 passing through opening 12 of sleeve 10 and head 16 resting against shoulders 13 and 14:. Shank 15 extendsclear through inner spring 1 and tapered end 24C is projected through opening 21 of sleeve 20. The spring, which is normally longer and of less diameter than the assembled length, is then compressed, and accordingly the caps are forced inwardly toward each other. vvlhen transverse slot 25 appears beyond the outer face of cap l19, key 26 is inserted and the respective ends of the key are slipped in any two of the diametrically opposed slots 22. The spring is then allowed to expand, and key 26 slips 'through the slots and rests on shoulders 23, securely holding cap 19 on the end of the spring. Cap 9 is held by head 16. It will be noted that both caps are securely locked against longitudinal or axial displacement by head 16 and key 26 within slots 22. By providing a plurality of diametrically opposed slots 22, the insertion of key 2G to fasten cap 19 at the end of the spring is greatly facilitated, it only being necessary to slightly shift cap 19 until a pair of diametrically opposed slots are in proper alinement with key 26; lVhen the caps are mounted in this manner Jdie opposite ends of spring 1 res*L lon the inner faces of the two sleeves 10, 20, and to prevent slipping of the spring its opposite ends 121i are tapered or flattened, as shown.

Each cap is provided with means for pre venting creeping of the nested helices and casing coils of the spring, and, inasmuch as the caps are substantially similar in this respect, both. Referring to 7, the inner face of a cap 9 is provided with opposite outer ahutments 27, 28, the respective end faces 27a, 28a of which are substantially plane and are engaged by the ends 7* and 8b of casing coils 7 and 8. T he abutments 27 and 28 taper away from their end faces at an angle.

which conforms substantially'to the inclina-- tion of the casing coils from the horizontal, and thus provide resting surfaces faces 27a, Q8" positively prevent creeping of the coils. The coils 7, 8 are tapered as at 7C, 8C, in order to permit their ends 7b, 8b to properly engage the abutments 27, 28. Nithin the space confined by the abutments 27, 28, is a second abutment 29 having a flat end face 29a extending radially inwardly to sleeve 10, and a face 29h opening circumferentially around the cap, and also inwardly toward the center of the cap. yabutment 29 is engaged by the end 3d of outer helix 3.

description of one will sufiioe forfor the ends of the respective casing coils. T he end T he inner surface of the cap is furthermore tapered circumferentially as shown at 30 to receivethe end 2 of inner helix 2. The end 2a of said coil is tapered, as shown, to ene prising a v plurality of intercalated coil springs. l

Q. In a friction spring, the `combination of a friction element having a cylindrical outer face and said friction element subject to radial expansion under axial stress, and a radially expansible and inherently axially resilient casing having a cylindrical inner face for cooperation with the cylindrical outer face of the friction element, and said casina` surrounding said friction element. 3. .lin a friction spring, the combination of a friction coil having a cylindrical outer face and said coil subject to radial expansion under axial stress, and a radially expansible and inherently axially resilient spring casing having a cylindrical inner face for cooperation with the cylindrical outer face of the friction coil and said spring casing surrounding the friction coil.

1. In a. friction spring, the combination of a. friction coil subject to radial expansion under axial stress, and a radially and axially, expansible and contractible casing surrounding said friction coil, said casing composed of a. plurality of intercalated coil springs.

5. The combination of a plurality of resilient helices nested one within the other in position to create friction between the convolutions under axial pressure, the outer helix having a cylindrical outer face, and a casing having a cylindrical inner face for coperaton with the outer cylindrical face of the'outer helix to resist radial stress in said helix and also expand and contract axially with said nested helices.

6. The combination of a plurality of re silient helices nested one within the other,

in position to create friction between the convolutions under casing composed ofy a plurality of intercalated coil springs, `said casing coils surrounding and frictionally engaging one of said nested helices to resist radial stress in said helices and also expand and contract axially with said helices.

7. The combination of a plurality of resilient helices nested onek within the other in position to create friction between the convolutions under axial pressure, a casing composed of a plurality of intercalated coil axial pressure, and a` iio also expand and contract axiallyy with saidv helices, and means for preventing creeping of said casing coils with respect to each other.

S. In a friction spring, the combination of a friction coil subject to radial expansion under axial stress, a casing surrounding said coil. comprising a plurality of intercalated coil springs, a cap at each end of the spring, means carried by the caps forpreventing creeping' of the casing coils with respect to each other, and means for preventing rotation of the caps with respect to each other.

9. In a friction spring, the combination of the main resilient elements, a cap at each end of the spring, a bar extending within said main resilient elements, and connecting said caps, and means carried by said bar for limiting the outward axial movement of the caps and for preventing' rotation of the caps with respect to each other.

l0. In a spring, the combination of the main resilient elem-ents, a casing surrounding said spring elements composed of a plurality of intercalated coil springs, a cap at each end of the spring, means carried by the caps for preventing creeping of the casing coils, a bar within said main resilient elements, and connections between said bar and the respective caps for preventing radial displacement of the caps and limiting the outward axial movement of the caps upon expansion of the spring without interfering with inc-vement of the caps toward each others upon compression of the spring.

ll. In a spring, the combination of the main resilient elements, a cap at each end of the spring, a, bar within the main resilient elements and upon which the caps are freely movable toward each other upon compression of the spring, and connections between 'said bar and the caps for preventing radial displacement of the caps and limiting their outward axial movement upon expansion of the spring.

l2. ln a spring', the combination of the main resilient elements7 a cap at each end of the spring, a bar within the main resilient elements and upon which the caps are freely movable toward each other upon compression of the spring, connections between said bar and the caps for preventing radial displacement of the caps and limiting their outward axialrmovement upon expansion of the spring, andV means whereby said caps and their connections are assembled on the spring when the resilient elements thereof are compressed.

13. ln a spring, the combination of a coil, a cap at each end of the coil, a shank within the coil having a head at one end, a sleeve on one of th-e caps receiving said head, and said head and sleeve shaped to lock the cap against radial and outward axial displacement on the shank, the other end of the shank extending into a central opening in the-other cap, diametrically opposed locking' slots in said cap, proximate said openinf, and a detachable key inserted transversely in the shank when the coil is compressed, and adapted to rest in said slots to lock said cap against radial and outward axial displacement upon release of the coil.

14. In a spring, the combination of a coil, a cap at each end of the coil, a shank within the coil having a head at one end, a sleeve on one of the caps receiving said head, and said head and sleeve shaped to lock the cap against radial and outward axial displacement on the shank, the other end of the shank extending into a central opening in the other cap, a series of locking slots in said cap extending' radially from said openinO', and a key carried by the shank and resting in diametrically opposed slcts of the series tolcck the cap against radial and outward axial displacement.

l5. A friction spring including, in combination, a coil subject to radial expansion under axial stress, and a radially expansible and inherently axially resilient casing surrounding the coil and having a cylindrical inner face for frictional cooperation with the outer face of the coil, the casing arranged to slip relatively to the coil and create friction therewith under pressure in a direction axially of the spring'.

16. The combination of a plurality of resilient helices nested one within the other in position to create friction between the convo-lutions under axial pressure, and a radially expansible and inherently axially resilient casing surrounding the outer helix and having a kcylindrical inner face for frictional cooperation with the outer face o-f the outer helix, the casing arranged to slip relative to the outer helix and create friction therewith under axial pressure.

RICHARD D. GALLAGHER, JR.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

